Photodeflection Method Research Articles

Studies of the Thermal Conductivity and Thermal Resistance of Solder Layers with Lead-Free Pastes by the Photodeflection Method

Studies of the Thermal Conductivity and Thermal Resistance of Solder Layers with Lead-Free Pastes by the Photodeflection Method

Studies of the thermal conductivity and thermal resistance of solder layers with lead-free pastes by the photodeflection method

The processes of heat removal from multijunction solar cells on a germanium substrate to AlN ceramics through a solder layer were studied by thermal wave photodeflection methods. Two types lead-free solder based on SnBi and SnAgCu were used under various pressure soldering conditions. The thermal conductivity and thermal resistance of the solder layers are compared. It is shown that the thermal conductivities of the solder layers differ from the reference data for the corresponding metal alloys, and in some cases may depend on the pressure during the brazing process. Keywords: thermal resistance, multi-junction solar cells, lead-free solder, non-destructive testing, thermal waves.

Photothermal measurement of the thermal parameters of volume materials and thin films by the photodeflection method

Photothermal measurement of the thermal parameters of volume materials and thin films by the photodeflection method

Optical losses characterization in waveguides through the photodeflection method

The photodeflection method is able to characterize the propa- gation losses in optical waveguides. The theory of the transverse con- figurations in air andin situ is reviewed. The procedure to determine the propagation loss coefficient is widely discussed. The experimental re- sults on two different Ti:LiNbO3 and glass channel waveguides are in good agreement with theory. © 1997 Society of Photo-Optical Instrumentation En- gineers.

Measurement of thermal parameters of solids by a modified photodeflection method

Alexej L. Glazov Kyrill L. Muratikov Physical-Technical Institute of RAS Politeknicheskaya 26 194021 St. Petersburg, Russia E-mail: klm@holo.ioffe.rssi.ru Abstract. A modified photodeflection method based on the wave optics approach is proposed for the thermal parameter measurement of volume materials and thin films. Experimental and theoretical results of the application of this method to measurements of the thermal parameters of solids are presented. It is shown that the modified photodeflection method can be used in a wide frequency range of thermal waves and provides a lower mean squared error between experimental and theoretical results in comparison with the ordinary method. © 1997 Society of Photo-Optical Instrumentation Engineers.

Thermal characterization by photodeflection method

The photodeflection technique is useful not only for thermal diffusivity measurements but also to supply a thermal imaging system. The experimental setup and the basic theoretical aspects for determining the temperature profile are discussed together with the experimental results on a semiconductor laser diode.

Thermal characterization of highT c superconductors through the photodeflection method

The photothermal deflection method has been used for thermal diffusivity measurements on bulk YBCO and BISCCO highTc superconductors. A cryostat set up is used to perform photothermal measurements from room temperature down to 77 K.

Thermal anisotropy of polymer carbon fiber composites as revealed by photodeflection methods

Thermal diffusivity for carbon fiber composites was measured using different fiber types and polymer matrices. Photothermal testing was performed in the various directions parallel and perpendicular to the carbon fiber axis by different photothermal configurations. By focusing the laser beam with a spherical lens, local inhomogeneities of the composite surface in the range of 10 μm are distinguished. When focusing is done with the aid of a cylindrical lens an averaging over larger scales of the photothermal deflected signal takes place. The results for various carbon fiber materials are discussed in terms of thermal diffusion lengths and thermal diffusivity values. It is shown that the thermal photodeflection method is suitable for measuring anisotropy in oriented carbon fiber composites.

Reply to ‘‘Comments on ‘The photothermal method applied to low thermal diffusivity measurements’ ’’ [Rev. Sci. Instrum. 66, 275 (1995)

An analysis of the thermal diffusivity data for a low diffusivity material is presented, showing that suitable experimental conditions must be carefully chosen to minimize the error in the measurements through the photodeflection method.

A phototermal experiment interpreted as evidence of electron-hole self-ordering in As-S chalcogenide glasses

The photodeflection method has been applied to detect optically induced changes of the refractive index due to self-organization of electrons and holes, trapped in the disordered structure of a chalcogenide glass of the As-S type.

Thermal diffusivity determination by the photodeflection method. The influence of wave optical effects

Possible approaches to thermal wave based measurement of thermal diffusivity are considered. The calculation of the transverse photodeflection signal in the framework of wave optics prove to be a more accurate approach compared to that of geometrical optics. The influence of the account of wave optical effects on the accuracy of the thermal diffusivity determination is theoretically analyzed under various conditions.

Optical losses characterization in channel waveguide through the photodeflection method

The photodeflection method applied to the propagation losses characterization in channel waveguides is discussed using two different set-up configurations. 3-D and 1-D models are presented in order to calculate the photodeflection angle. The effects on the measurement of any set-up misalignment are studied. Different ways for determining the propagation losses are shown. Comparison between theoretical and experimental results for Ti : LiNbO3 and a glass channel waveguide is also reported.

Mirror temperature of a semiconductor diode laser studied with a photothermal deflection method

The mirror temperature response of a diode laser to injection current is studied through the photodeflection method. A theoretical model is presented together with some experimental measurements. Theoretical results are compared with experimental measurements for an AlGaAs quantum well laser diode.

On the photodeflection method applied to low thermal diffusivity measurements

The photodeflection method when applied to measure the low thermal diffusivity of some materials gives inconsistent results. In this article a way to extend the thermal diffusivity range of measurements using the phase of the photodeflection signal is presented. A comparison with computer simulations and experimental results shows good agreement.

Refractive Index Changes in CdSxSe1 − xdoped Glasses Through the Photodeflection Method

Abstract Using the photo-deflection method in quasi c.w. regime refractive index variations of CdSx Se1 − x doped glasses have been observed consisting of two independent contributions Δn = Δnt + Δne. The photothermal term Δnt = (dn/dT) ΔT (ΔT is the temperature increase) is positive and slow in time, the electronic term Δne is negative and fast. The electronic term appears at first due to a reversible contribution (during a time scale of 1/ω, where ω is the chopper frequency) and after a time of a few tenths of seconds disappears irreversibly. It is attributed to a redistribution in space and energy levels of electrons in the semiconductor microcrystals. This redistribution is large enough when the electron relaxation is not too fast. The consequent refractive index change decreases in time and disappears under prolonged laser irradiation. A model is presented in which the presence of traps is taken into account.

Photodeflection method applied to the thermal characterization of CuCl and Cu 2O glasses

Non-linear thermo-optical properties of doped glasses can be studied with the help of the photodeflection method. We report thermal diffusivity measurements obtained through the photodeflection method in its transverse configuration in both quasi-continuous and pulsed irradiation. The photodeflection method was suitably optimized for the case of glasses with very low thermal diffusivity.